JP2015117998A - Electromagnetic induction type position detector and detection method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electromagnetic induction type position detector and detection method by which miniaturization is possible and interference errors do not occur.SOLUTION: An electromagnetic induction type position detector comprises: a stator 11 which includes first and second main patterns 13, 14, and first and second sub patterns 15, 16; and a rotor 12 including a main pattern part 17a and a sub pattern part 17b in which adjacent comb-shaped electrodes of the main pattern part 17a and the sub pattern part 17b are connected to each other to be one loop. When excitation current is supplied to the first and second main patterns 13, 14, excitation voltage excited at the main pattern part 17a is detected through the sub pattern part 17b by use of the first and second sub patterns 15, 16. When excitation current is supplied to the first and second sub patterns 15, 16, excitation voltage excited at the sub pattern part 17b is detected through the main pattern part 17a by use of the first and second main patterns 13, 14.

Description

  The present invention relates to an electromagnetic induction type position detector and a detection method for detecting the position of a detection target by electromagnetic induction.

  An inductive scale, which is an electromagnetic induction type position detector, is applied to position detection units of various machines such as machine tools, automobiles, and robots. Induct thin type scales include a linear type linear scale and a rotary type rotary scale. For example, the linear scale is installed on a linear moving part such as a linear moving shaft of a machine tool, and the moving part The rotary scale is installed in a rotating part such as a rotating shaft of a machine tool, for example, and detects the rotational position (rotational angle) of the rotating part.

  Both the linear scale and the rotary scale detect positions by electromagnetic induction of coil patterns arranged in parallel and face to face. This detection principle will be described with reference to FIG. 4 is a diagram for explaining the principle of the linear scale, FIG. 4A is a diagram showing the slider and the scale of the linear scale side by side, and FIG. 4B is an electromagnetic coupling of the slider and the scale. It is a figure which shows a degree. 4 (a) and 4 (b) show the principle diagram of the linear scale. The principle of the rotary scale is the same as this, and the rotary scale stator and rotor are connected to the linear scale slider and scale. Corresponds to each.

  As shown in FIG. 4A, the detection unit of the linear scale includes a slider 41 serving as a primary side plate member and a scale 42 serving as a secondary side plate member. In the linear scale, the slider 41 has a first slider coil 43 serving as a first primary coil and a second slider coil 44 serving as a second primary coil. The scale 42 has a scale coil 45 serving as a secondary side coil. Each of these coils 43, 44, 45 is formed in a zigzag shape and is linear.

  The slider 41 (first slider coil 43 and second slider coil 44) and the scale 42 (scale coil 45) are arranged in parallel and face to face with a predetermined gap g therebetween. Further, as shown in FIG. 4A, the first slider coil 43 and the first slider coil 44 are displaced from each other by a quarter pitch with respect to one pitch of the scale coil 45 (the phase is 90 degrees). Is out of alignment).

  In this linear scale, when an excitation current (alternating current) is passed through the first slider coil 43 and the second slider coil 44, the movement of the slider 41 causes the first slider coil 43, the second slider coil 44, and the scale coil 45 to move. As shown in FIG. 4B, the degree of electromagnetic coupling between the first slider coil 43 and the second slider coil 44 and the scale coil 45 periodically changes according to the change in the relative positional relationship. For this reason, an excitation voltage that periodically changes is generated in the scale coil 45.

  As one example of detecting the position, a first excitation current Ia as shown in the following equation (1) is passed through the first slider coil 43, and a second excitation current Ib as shown in the following equation (2) is supplied to the second slider. When flowing through the coil 44, an excitation voltage V as shown in the following formula (3) is generated in the scale coil 45 by electromagnetic induction between the first slider coil 43 and the second slider coil 44 and the scale coil 45. And the peak amplitude Vp which sampled following formula (3) can be represented as shown in following formula (4).

Ia = −I · cos (kα) · sin (ωt) (1)
Ib = I · sin (kα) · sin (ωt) (2)
V = K (g) · I · sin (k (X−α)) · sin (ωt) (3)
Vp = K (g) · I · sin (k (X−α)) (4)

  Here, “I” is the magnitude of the excitation current, “k” is 2π / p, this “p” is the length of one pitch of the scale coil 45 (angle on the rotary scale), and “ω” is the excitation current. (AC current) angular frequency, “t” is time, and “α” is an excitation position. “K (g)” is a coupling coefficient depending on the coupling strength such as the gap g between the first slider coil 43 and the second slider coil 44 and the scale coil 45, and “X” is the scale coefficient. It is a position displacement (movement position).

  In the above equation (4), by causing the excitation position α to follow the position displacement X and controlling so that Vp = 0, α = X can be obtained as the detection position.

Japanese Patent No. 3806358

  The rotary scale includes a stator corresponding to the slider of the linear scale and a rotor corresponding to the scale of the linear scale. As shown in FIG. 5, a scale pattern area 52 in which a scale coil is provided and a rotary transformer area 53 in which a rotary transformer is provided are arranged on a rotor 51 that is a movable part of the rotary scale. This rotary transformer is necessary for transmitting the excitation voltage V generated in the scale coil of the rotor 51 to the stator without contact. Thus, since a space for providing the rotary transformer is required, it is difficult to secure a space for providing the rotary transformer in the small-diameter (small) rotary scale. Even if there is a space, an interference error occurs if the scale coil and the rotary transformer are close (need to be separated by 1 cm or more).

  The present invention has been made in view of the above problems, and an object of the present invention is to provide an electromagnetic induction position detector and a detection method that can be reduced in size and that do not generate interference errors.

An electromagnetic induction type position detector according to the first invention for solving the above-mentioned problems is as follows.
In the electromagnetic induction type position detector that detects the position using electromagnetic induction,
A primary side plate member (arranged in parallel) having a primary side main pattern and a primary side sub-pattern composed of planar coil patterns of comb-shaped poles with different pitches;
A secondary side main pattern and a secondary side subpattern consisting of planar coil patterns of comb-like poles having different pitches are disposed (arranged in parallel), and the secondary side main pattern and the secondary side subpattern are adjacent to each other. The comb-shaped poles are connected to each other, and a secondary side plate member in which the secondary side main pattern and the secondary side subpattern are formed into one loop,
The switching between the primary side main pattern and the primary side sub pattern is controlled to supply an excitation current to either the primary side main pattern or the primary side sub pattern, and from the other side to the secondary side A control unit that detects an excitation voltage flowing in the main pattern or the secondary side sub-pattern,
The primary side plate member and the secondary side plate member are opposed to each other, with the primary side main pattern and the primary side sub pattern and the secondary side main pattern and the secondary side sub pattern facing each other.
The controller is
When the excitation current is supplied to the primary side main pattern, the excitation voltage of the secondary side main pattern excited by the excitation current of the primary side main pattern is transferred to the primary side via the secondary side subpattern. Detect using sub-pattern,
When the excitation current is supplied to the primary side subpattern, the excitation voltage of the secondary side subpattern excited by the excitation current of the primary side subpattern is transmitted through the secondary side main pattern to the primary side subpattern. Detection is performed using a main pattern.

An electromagnetic induction type position detector according to a second invention for solving the above-mentioned problems is as follows.
In the electromagnetic induction type position detector according to the first invention,
The controller is
A drive circuit for supplying an excitation current to the primary main pattern or the primary sub pattern;
A pickup circuit that detects an excitation voltage flowing through the secondary main pattern or the secondary sub pattern using the primary main pattern or the primary sub pattern, and
A switch unit that switches the drive circuit to either the primary side main pattern or the primary side sub pattern, and switches the pickup circuit to the other side of the primary side main pattern or the primary side sub pattern, and
The controller is
When supplying the excitation current to the primary main pattern, the switch unit switches the drive circuit to the primary main pattern and switches the pickup circuit to the primary sub pattern to be excited by the excitation current. The secondary side main pattern excitation voltage is detected through the secondary side subpattern, using the primary side subpattern,
When supplying the excitation current to the primary side subpattern, the switch unit switches the drive circuit to the primary side subpattern, and the pickup circuit is switched to the primary side main pattern to be excited by the excitation current. The excitation voltage of the secondary side sub-pattern is detected using the primary side main pattern via the secondary side main pattern.

An electromagnetic induction type position detector according to a third invention for solving the above-mentioned problems is as follows.
In the electromagnetic induction position detector according to the first or second invention,
In the case of a rotary electromagnetic induction position detector having a rotor and a stator,
The primary side plate member is the stator, and each of the primary side main pattern and the primary side sub pattern is formed in an annular shape as a whole,
The secondary plate member is the rotor, and the secondary main pattern and the secondary sub pattern are formed in an annular shape as a whole.

An electromagnetic induction type position detector according to a fourth invention for solving the above-mentioned problems is as follows.
In the electromagnetic induction position detector according to the first or second invention,
When a linear electromagnetic induction type position sensor having a slider and a scale is used,
The primary side plate member is the slider, and each of the primary side main pattern and the primary side sub pattern is formed in a linear shape, and
The secondary side plate member is the scale, and the secondary side main pattern and the secondary side sub-pattern are formed so as to be linear as a whole.

An electromagnetic induction type position detection method according to a fifth invention for solving the above-described problem is
A detection method using the electromagnetic induction type position detector according to any one of the first to fourth inventions,
The primary side main pattern includes a first primary side main pattern and a second primary side main pattern arranged with a phase shifted by 90 degrees from the first primary side main pattern,
The primary side subpattern includes a first primary side subpattern and a second primary side subpattern arranged with a phase shifted by 90 degrees from the first primary side subpattern,
The controller is
The first excitation current Ia shown in Formula 1 is supplied to the first primary side main pattern or the first primary side sub pattern, and the second primary side main pattern or the second primary side sub pattern is supplied to the first primary side main pattern or the first primary side sub pattern. , Supplying the second excitation current Ib shown in Equation 1,
In the secondary side main pattern or the secondary side sub-pattern, the excitation voltage V shown in Equation 1 is generated,
In the first primary side sub pattern or the first primary side main pattern, the first excitation voltage Vs shown in Equation 1 is detected, and in the second primary side sub pattern or the second primary side main pattern, The second excitation voltage Vc shown in Equation 1 is detected,
After the second excitation voltage Vc is phase-shifted by 90 degrees, the second excitation voltage Vc is combined with the first excitation voltage Vs to derive a combined voltage Vg shown in Equation 1.
By making the excitation position α follow the position displacement X so that B = 0 in the combined voltage Vg, α = X is obtained as a detection position.

  According to the present invention, since a rotary transformer is not required, the size can be reduced and an interference error does not occur.

It is a top view which shows an example of the primary side coil pattern and secondary side coil pattern of an electromagnetic induction type position detector as embodiment of the electromagnetic induction type position detector and detection method which concern on this invention. It is a top view which shows the structure in the rotor of the secondary side coil pattern shown in FIG. It is a figure which shows the circuit structure used for the primary side coil pattern and secondary side coil pattern which were shown in FIG. 1, FIG. It is a figure explaining the principle of the linear scale which is an electromagnetic induction type position detector, (a) is a figure which shows the slider and scale of a linear scale side by side, (b) is a figure which shows the electromagnetic coupling degree of a slider and a scale. It is. It is a top view which shows the rotor of the rotary scale which is an electromagnetic induction type position detector. It is a top view which shows the secondary side coil pattern in the rotor of the absolute value rotary scale which is an electromagnetic induction type position detector.

  Embodiments of an electromagnetic induction type position detector and a detection method according to the present invention will be described with reference to FIGS. Here, a rotary scale is described as an example, but the present invention can also be applied to a linear scale.

Example 1
FIG. 1 is a plan view showing an example of a primary-side coil pattern and a secondary-side coil pattern of a rotary scale serving as an electromagnetic induction type position detector of the present embodiment. FIG. 2 is a plan view showing the configuration of the rotor of the secondary coil pattern shown in FIG. FIG. 3 is a diagram showing a circuit configuration used for the primary side coil pattern and the secondary side coil pattern shown in FIGS.

  First, the absolute value rotary scale for detecting the absolute value of the rotation angle (absolute angle) will be described with reference to FIG. 6 together with FIG. 5 described above. Note that FIG. 6 corresponds to a region surrounded by an alternate long and short dash line in FIG.

  As shown in FIG. 6 for a part of the rotor of the absolute value rotary scale, a planar coil pattern having a different pitch (repetition cycle) folded in a zigzag shape in a comb shape as a secondary side coil pattern. A main pattern 55 and a sub pattern 56 are formed, and these are formed so as to be entirely annular on the entire circumference in the same plane. Corresponding to each of the main pattern 55 and the sub pattern 56, the stator also has a main pattern composed of planar coil patterns with different pitches, which are folded back in a zigzag shape as a slider coil serving as a primary coil pattern. Sub-patterns are formed, and these are formed so as to form an annular shape all around the same plane (not shown).

  Then, the rotor and the stator are opposed to each other so that the main pattern 55 and the sub pattern 56 constituting the scale coil on the rotor side and the main pattern and the sub pattern constituting the slider coil on the stator side face each other. It becomes the composition.

  The principle of position detection (angle detection) is as described above, and the absolute angle of the rotor can be obtained from the difference between detection angles obtained from the main pattern side and the sub pattern side. At this time, the voltage obtained from each of the main pattern side and the sub-pattern side is transmitted from the rotor side to the stator side via the rotary transformer as described above. The presence of this rotary transformer is the rotary scale. Was preventing the miniaturization.

  As a result of intensive studies by the present inventor, in the absolute value rotary scale having the main pattern and the sub pattern, since the detection in the main pattern and the detection in the sub pattern are performed separately, one of the patterns is not used. Thus, it has been found that it is possible to perform signal transmission using an unused pattern instead of the rotary transformer. That is, when the main pattern is detected, the sub pattern can be used to transmit a signal from the rotor side to the stator side, and when the sub pattern is detected, the main pattern is used to transfer the rotor side to the stator side. It was found that signal transmission was possible.

  However, since it is difficult to perform signal transmission using the unused pattern with the main pattern and sub pattern configuration shown in FIG. 6, the configuration of the main pattern and sub pattern is the configuration shown in FIG. It is said.

  Specifically, as shown in FIG. 1, the scale pattern 17 on the rotor 12 (secondary side plate member) side includes a main pattern portion 17a (secondary side main pattern) composed of a planar coil pattern having a plurality of comb-shaped poles. The main pattern portion 17a is composed of a sub-pattern portion 17b (secondary side sub-pattern) composed of a planar coil pattern having a plurality of comb-shaped poles having a different pitch, and a plurality of connection lines 17c. The main pattern portion 17a and the sub-pattern portion 17b are also folded in a zigzag shape in a U-shape, and the pitch of the comb-shaped pole (the angle of one comb-shaped pole) is the sub-pattern portion 17b. Is made smaller (pitch Pa> pitch Pb).

  Regarding the pattern shape of the scale pattern 17, the main pattern portion 17a is based on the conventional main pattern, and the sub pattern portion 17b is also based on the conventional sub pattern, and is arranged in parallel. The adjacent comb-shaped poles 17a and the sub-pattern part 17b (portions that have been U-shaped in the past) are connected to each other by connection lines 17c, so that the whole is formed as one loop (one-stroke line). In FIG. 1, for reference, a conventional pattern portion (a portion indicated by a dot) is indicated by reference numeral 17d.

  As described above, since the pitch Pa of the main pattern portion 17a and the pitch Pb of the sub pattern portion 17b are different, a part of the connection lines 17c is one line together with the lines of the main pattern portion 17a and the lines of the sub pattern portion 17b. Although they are arranged and connected in a straight line, many connection lines 17c are arranged and connected obliquely with respect to the lines of the main pattern portion 17a and the lines of the sub pattern portion 17b.

  Also, the slider pattern on the stator 11 (primary side plate member) side corresponds to the main pattern portion 17a on the rotor 12 side as in the prior art, and the first main pattern 13 (consisting of a planar coil pattern having a plurality of comb-shaped poles). The first main pattern 13 and the second main pattern 14 correspond to the first main pattern 13) and the second main pattern 14 (second primary main pattern) and the sub pattern portion 17b on the rotor 12 side. Is a configuration having a first sub-pattern 15 (first primary-side sub-pattern) and a second sub-pattern 16 (second primary-side sub-pattern) composed of planar coil patterns having a plurality of comb-shaped poles with different pitches. . The first main pattern 13 and the second main pattern 14, and the first sub pattern 15 and the second sub pattern 16 are arranged in parallel. The first main pattern 13 and the first sub pattern 15 become the first primary coil, and the second main pattern 14 and the second sub pattern 16 become the second primary coil.

  Further, the first main pattern 13 and the second main pattern 14 are shifted by a quarter pitch position (the phase is shifted by 90 degrees) on the basis of one pitch of the main pattern portion 17a, and the sub pattern portion 17b. The first sub-pattern 15 and the second sub-pattern 16 are shifted from each other by a quarter pitch position (the phase is shifted by 90 degrees).

  As in the prior art, the scale pattern on the rotor 12 side so that the main pattern portion 17a of the scale pattern 17 on the rotor 12 side faces the first main pattern 13 and the second main pattern 14 on the stator 11 side. The rotor 12 and the stator 11 are disposed so as to face each other so that the 17 sub-pattern portions 17b face the first sub-pattern 15 and the second sub-pattern 16 on the stator 11 side.

  The scale pattern 17 and the slider pattern described above can be produced using, for example, a printed circuit board, but the first main pattern 13 and the second main pattern 14, the first sub pattern 15 and the first pattern constituting the slider pattern, respectively. Since the two sub-patterns 16 are separated patterns and wiring is performed individually, the sub-patterns 16 may be individually manufactured using a printed circuit board.

  In FIG. 1, for the sake of simplicity, the overall shape is linear and the length is shortened. However, in the rotary scale, as shown in FIG. 2, a circular rotor is used. According to the shape of 12, the stator pattern 17 is formed so that the whole becomes an annular shape. The same applies to the slider pattern. In addition, if it is not a rotary scale but a linear scale, the shape as shown in FIG. 1 may be sufficient.

  Unlike the conventional case, the scale pattern 17 on the rotor 12 side is configured as shown in FIGS. 1 and 2, so that a rotary transformer is not required at all. Therefore, the diameter of the rotor can be reduced, and as a result, the entire rotary scale can be reduced in size. Further, since there is no rotary transformer, the interference error itself does not occur.

  Next, a circuit configuration used for the scale pattern 17 will be described with reference to FIG. In FIG. 3, the scale pattern 17 is illustrated as being cut at an end portion for convenience, but is actually connected at a connection point L to form one loop.

  As described above, the rotary scale according to the present embodiment has the first main pattern 13 and the second main pattern 14 on the stator 11 side, the first sub pattern 15 and the second sub pattern 16, and the main scale on the rotor 12 side. A scale pattern 17 including a pattern portion 17a and a sub pattern portion 17b is provided.

  Further, the rotary scale of this embodiment includes a SIN drive circuit 21 that supplies an alternating excitation current to the first main pattern 13 and a COS that supplies an alternating excitation current different from the SIN drive circuit 21 to the second main pattern 14. A SIN pickup circuit 23 that detects the excitation voltage of the scale pattern 17 using the drive circuit 22 and the first main pattern 13, and a COS pickup circuit that detects the excitation voltage of the scale pattern 17 using the second main pattern 14. 24 and a switch unit 25 for switching between them.

  Further, the rotary scale of this embodiment includes a SIN drive circuit 31 that supplies an alternating excitation current to the first sub pattern 15 and a COS that supplies an alternating excitation current different from the SIN drive circuit 31 to the second sub pattern 16. A SIN pickup circuit 33 that detects the excitation voltage of the scale pattern 17 using the drive circuit 32, the first sub pattern 15, and a COS pickup circuit that detects the excitation voltage of the scale pattern 17 using the second sub pattern 16. 34 and a switch unit 35 for switching between them.

  In the switch unit 25, any one of the SIN drive circuit 21 and the COS drive circuit 22, and the SIN pickup circuit 23 and the COS pickup circuit 24 is selected. Specifically, when the excitation current is supplied (in the drive mode), the SIN drive circuit 21 and the COS drive circuit 22 are selected by the switch unit 25, and each of the first main pattern 13 and the second main pattern 14 is selected. Electrically connected. When the excitation voltage is detected (in the pickup mode), the SIN pickup circuit 23 and the COS pickup circuit 24 are selected by the switch unit 25 and are electrically connected to the first main pattern 13 and the second main pattern 14 respectively. Connected to.

  Similarly, in the switch unit 35, any one of the SIN drive circuit 31 and the COS drive circuit 32, and the SIN pickup circuit 33 and the COS pickup circuit 34 is selected. Specifically, when the excitation current is supplied (in the drive mode), the SIN drive circuit 31 and the COS drive circuit 32 are selected by the switch unit 35, and the first sub pattern 15 and the second sub pattern 16 are respectively selected. Electrically connected. When the excitation voltage is detected (in the pickup mode), the SIN pickup circuit 33 and the COS pickup circuit 34 are selected by the switch unit 35 and are electrically connected to the first sub pattern 13 and the second sub pattern 14, respectively. Connected to.

  Further, when the SIN drive circuit 21 and the COS drive circuit 22 are selected by the switch unit 25, the SIN pickup circuit 33 and the COS pickup circuit 34 are selected by the switch unit 35. On the other hand, when the SIN drive circuit 31 and the COS drive circuit 32 are selected by the switch unit 35, the SIN pickup circuit 23 and the COS pickup circuit 24 are selected by the switch unit 25.

  That is, when an excitation current is supplied from the SIN drive circuit 21 and the COS drive circuit 22 selected by the switch unit 25 to the first main pattern 13 and the second main pattern 14, respectively, the main pattern of the scale pattern 17 is generated by the supplied excitation current. The excitation voltage excited by the unit 17a is transmitted to the first subpattern 15 and the second subpattern 16 through the subpattern unit 17b, and the SIN pickup circuit 33 and the COS pickup circuit 34 selected by the switch unit 35. Thus, each excitation voltage is detected. This is called “main pattern excitation-sub-pattern detection”.

  Similarly, when an excitation current is supplied from the SIN drive circuit 31 and the COS drive circuit 32 selected by the switch unit 35 to the first sub pattern 15 and the second sub pattern 16, respectively, the scale pattern 17 is subtracted by the supplied excitation current. The excitation voltage excited by the pattern unit 17b is transmitted to the first main pattern 13 and the second main pattern 14 via the main pattern unit 17a, and the SIN pickup circuit 23 and the COS pickup circuit selected by the switch unit 25. Each excitation voltage is detected by 24. This is called “sub-pattern excitation-main pattern detection”.

  Such control and calculation shown below are controlled and calculated by the calculation control device 20.

  Next, control and calculation of the absolute position (absolute angle) in the rotary scale of this embodiment will be described below. Here, “main pattern excitation—sub pattern detection” will be described, but the same control and calculation may be performed in the case of “sub pattern excitation—main pattern detection”.

(Step 1)
Excitation currents are supplied from the SIN drive circuit 21 and the COS drive circuit 22 selected by the switch unit 25 to the first main pattern 13 and the second main pattern 14, respectively. Basically, as in the prior art, a first excitation current Ia as shown in the above equation (1) is passed through the first main pattern 13, and a second excitation current Ib as shown in the above equation (2) Flow in main pattern 14. Then, due to electromagnetic induction between the first main pattern 13 and the second main pattern 14 and the main pattern portion 17a of the scale pattern 17, the main pattern portion 17a has the following equation (5) as in the above equation (3). An excitation voltage V as shown in FIG.

V = A · sin (ωt) (5)
However, A = Km · I · sin (k (X−α)), and “Km” is a gap g between the first main pattern 13 and the second main pattern 14 and the main pattern portion 17 a of the scale pattern 17. It is a coupling coefficient depending on the strength of coupling.

(Step 2)
The excitation voltage V excited in the main pattern portion 17a of the scale pattern 17 causes a current to flow in the sub-pattern portion 17b, and the excitation voltage is applied to the first sub-pattern 15 and the second sub-pattern 16 respectively. Occur. These excitation voltages are respectively detected by the SIN pickup circuit 33 and the COS pickup circuit 34 selected by the switch unit 35. The excitation voltage detected by the SIN pickup circuit 33 in the first sub pattern 15 is Vs. Assuming that the excitation voltage detected in the second sub-pattern 16 by the COS pickup circuit 34 is Vc, the following expressions (6) and (7) can be expressed.

Vs = B · sin θ · sin (ωt) (6)
Vc = B · cos θ · sin (ωt) (7)
However, B = Ks · A = Ks · Km · I · sin (k (X−α)), and “Ks” is the sub pattern portion 17b of the scale pattern 17, the first sub pattern 15 and the second sub pattern. 16 is a coupling coefficient that depends on the strength of coupling such as a gap g between 16 and 16. “Θ” is the position (angle) of the scale pattern 17.

(Step 3)
In the arithmetic and control unit 21, the excitation voltage Vc is phase-shifted by 90 degrees by a phase shift circuit (not shown) provided in the arithmetic and control unit 21. Then, the excitation voltage Vc can be expressed by the following formula (8).
Vc = B · cos θ · cos (ωt) (8)

(Step 4)
When the excitation voltage Vs shown in the above equation (6) and the excitation voltage Vc shown in the above equation (8) are combined, the following equation (9) can be derived for the combined voltage Vg.
Vg = B · sin θ · sin (ωt) + B · cos θ · cos (ωt) = B · cos (ωt−θ) (9)

(Step 5)
In the above equation (9), if control is performed so that B = 0, that is, excitation with respect to the position displacement X in B = Ks · A = Ks · Km · I · sin (k (X−α)). By controlling the position α to follow B = 0, α = X is obtained as a detection position, and thereby the main position Xm of the main pattern portion 17a of the scale pattern 17 is obtained.

  Also for “sub-pattern excitation-main pattern detection”, the sub-position Xs of the sub-pattern portion 17b of the scale pattern 17 is obtained by performing the same control and calculation as in steps 1 to 5 above.

  Then, the absolute position (absolute angle) of the rotor 11 can be obtained from the difference between the main position Xm and the sub position Xs.

  Here, the case of the rotary scale is illustrated, but in the case of the linear scale, the circuit configuration (especially wiring) can be simplified.

  The present invention is applicable to scales, encoders, magnetic sensors, electromagnetic sensors, and the like.

DESCRIPTION OF SYMBOLS 11 Stator 12 Rotor 13 1st main pattern 14 2nd main pattern 15 1st sub pattern 16 2nd sub pattern 17 Scale pattern 17a Main pattern part 17b Sub pattern part 20 Arithmetic control unit 21, 31 SIN drive circuit 22, 32 COS drive Circuit 23, 33 SIN pickup circuit 24, 34 COS pickup circuit 25, 35 Switch section

Claims (5)

In the electromagnetic induction type position detector that detects the position using electromagnetic induction,
A primary side plate member having a primary side main pattern and a primary side sub-pattern composed of planar coil patterns of comb-shaped poles having different pitches from each other;
Each of the comb-shaped poles adjacent to each other of the secondary-side main pattern and the secondary-side sub-pattern has a secondary-side main pattern and a secondary-side sub-pattern composed of planar coil patterns of comb-shaped poles having different pitches from each other. A secondary side plate member that connects the secondary side main pattern and the secondary side sub-pattern into one loop;
The switching between the primary side main pattern and the primary side sub pattern is controlled to supply an excitation current to either the primary side main pattern or the primary side sub pattern, and from the other side to the secondary side A control unit that detects an excitation voltage flowing in the main pattern or the secondary side sub-pattern,
The primary side plate member and the secondary side plate member are opposed to each other, with the primary side main pattern and the primary side sub pattern and the secondary side main pattern and the secondary side sub pattern facing each other.
The controller is
When the excitation current is supplied to the primary side main pattern, the excitation voltage of the secondary side main pattern excited by the excitation current of the primary side main pattern is transferred to the primary side via the secondary side subpattern. Detect using sub-pattern,
When the excitation current is supplied to the primary side subpattern, the excitation voltage of the secondary side subpattern excited by the excitation current of the primary side subpattern is transmitted through the secondary side main pattern to the primary side subpattern. An electromagnetic induction type position detector characterized by detecting using a main pattern. The electromagnetic induction type position detector according to claim 1,
The controller is
A drive circuit for supplying an excitation current to the primary main pattern or the primary sub pattern;
A pickup circuit that detects an excitation voltage flowing through the secondary main pattern or the secondary sub pattern using the primary main pattern or the primary sub pattern, and
A switch unit that switches the drive circuit to either the primary side main pattern or the primary side sub pattern, and switches the pickup circuit to the other side of the primary side main pattern or the primary side sub pattern, and
The controller is
When supplying the excitation current to the primary main pattern, the switch unit switches the drive circuit to the primary main pattern and switches the pickup circuit to the primary sub pattern to be excited by the excitation current. The secondary side main pattern excitation voltage is detected through the secondary side subpattern, using the primary side subpattern,
When supplying the excitation current to the primary side subpattern, the switch unit switches the drive circuit to the primary side subpattern, and the pickup circuit is switched to the primary side main pattern to be excited by the excitation current. An electromagnetic induction type position detector, wherein the excitation voltage of the secondary side sub pattern is detected using the primary side main pattern via the secondary side main pattern. In the electromagnetic induction type position detector according to claim 1 or 2,
In the case of a rotary electromagnetic induction position detector having a rotor and a stator,
The primary side plate member is the stator, and each of the primary side main pattern and the primary side sub pattern is formed in an annular shape as a whole,
An electromagnetic induction position detector, wherein the secondary plate member is the rotor, and the secondary main pattern and the secondary sub pattern are formed in an annular shape as a whole. In the electromagnetic induction type position detector according to claim 1 or 2,
When a linear electromagnetic induction type position sensor having a slider and a scale is used,
The primary side plate member is the slider, and each of the primary side main pattern and the primary side sub pattern is formed in a linear shape, and
The electromagnetic induction type position detector, wherein the secondary side plate member is the scale, and the secondary main pattern and the secondary sub pattern are formed in a straight line as a whole. A detection method using the electromagnetic induction type position detector according to any one of claims 1 to 4,
The primary side main pattern includes a first primary side main pattern and a second primary side main pattern arranged with a phase shifted by 90 degrees from the first primary side main pattern,
The primary side subpattern includes a first primary side subpattern and a second primary side subpattern arranged with a phase shifted by 90 degrees from the first primary side subpattern,
The controller is
The first excitation current Ia shown in Formula 1 is supplied to the first primary side main pattern or the first primary side sub pattern, and the second primary side main pattern or the second primary side sub pattern is supplied to the first primary side main pattern or the first primary side sub pattern. , Supplying the second excitation current Ib shown in Equation 1,
In the secondary side main pattern or the secondary side sub-pattern, the excitation voltage V shown in Equation 1 is generated,
In the first primary side sub pattern or the first primary side main pattern, the first excitation voltage Vs shown in Equation 1 is detected, and in the second primary side sub pattern or the second primary side main pattern, The second excitation voltage Vc shown in Equation 1 is detected,
After the second excitation voltage Vc is phase-shifted by 90 degrees, the second excitation voltage Vc is combined with the first excitation voltage Vs to derive a combined voltage Vg shown in Equation 1.
An electromagnetic induction type position detection method, wherein α = X is obtained as a detection position by causing the excitation position α to follow the position displacement X so that B = 0 in the composite voltage Vg.